TITLE:
Production and Characterization of Activated Carbon from Soybean Hulls for Methylene Blue Dye Removal: Adsorption Kinetics, Adsorption Isotherms and Intraparticle Diffusion
AUTHORS:
Sodoadika Akpolou, Samadou Sanni, Clément Kolawole Balogoun, Ibrahim Tchakala, Moursalou Koriko, Gado Tchangbedji
KEYWORDS:
Soybean Hulls, Activated Carbon Characterization, Methylene Blue Dye, Adsorption
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.16 No.8,
August
27,
2026
ABSTRACT: Dyes represent an important category of pollutants that are harmful for aquatic organisms, human health and the environment. The present study aims to prepare activated soybean hulls carbon (ASHC) in order to apply for the removal of methylene blue (MB) dye. To this end, the phosphoric acid chemical method was adopted for the synthesis of activated carbon from soybean hulls. Furthermore, physicochemical and textural characterizations were performed, including analyses by thermogravimetric (TG-DTG) analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and the Lopez-Ramon method (1999). An experimental study of MB dye removal using the batch method was carried out for ASHC adsorption capacity evaluation. First-order and second-order adsorption kinetics, Langmuir and Freundlich adsorption isotherms, and intraparticle diffusion were determined. Specifically, the mass yield and low ash content, parameters indicating the amorphous state of the adsorbent, and the pH at the zero-charge point (= 4.25) were determined. XRD indicates the absence of crystallization in the activated charcoal. SEM at 25 μm illustrates the picture of the surface of the charcoal. EDX analysis of the activated charcoal reveals the presence of carbon and oxygen. Characterization and experimental results show that the ASHC is amorphous. Experimental adsorption studies reveal an MB removal rate exceeding 96%; the pseudo-first-order kinetic model, the second-order model, and intraparticle diffusion were investigated. ASHC is therefore a potential alternative adsorbent for wastewater treatment. The results of the adsorption data were better described by pseudo-second order kinetic model. It is revealed that both Langmuir isotherm model and Freundlich isotherm model fit the equilibrium data.